An illustration of NASA's Nuclear Thermal Propulsion Systems

According to a December 29, 2023 article in the Times of India, India's nuclear sector will power future Indian space missions through nuclear propulsion.

The article says that ISRO chairman S Somanath announced plans to collaborate with the department of atomic energy. The article also mentions that the radioisotope heating units in Chandrayaan-3's propulsion module worked well, which generated enthusiasm.

A nuclear rocket engine uses a fission reactor to create high temperatures. The engine then transfers this heat to a liquid propellant, which is expanded and exhausted through a nozzle to propel the spacecraft. Nuclear thermal rockets work similarly to chemical rockets. A heat source releases thermal energy into a gaseous propellant inside the engine. A nozzle at one end allows the propellant to expand away from the vehicle, carrying momentum.

According to a Business Today article from August 14, 2023, ISRO is collaborating with the Bhabha Atomic Research Centre (BARC) to develop a nuclear-powered engine for deep space missions. The article says that chemical engines are suitable for satellite thrusters, but they are not adequate for interplanetary missions due to fuel constraints.

His statement assumes significance with global space agencies entering the nuclear power sector. He said the first phase of the Bharatiya Antariksh Station (Space Station) will be ready by 2028, while the entire facility will be completed in 2035. “It will be an international platform for collaborative research,” he said, adding that the space station will be a gateway for interplanetary missions, microgravity studies, space biology, medicine and research. Speaking on other projects, Somanath said ISRO is working on an Integrated Lunar Exploration Roadmap, which, among other things, envisages setting up a moon base habitat at a lower cost, compared to other nations. The lunar roadmap also includes a lunar sample return mission.

A nuclear thermal rocket can allow for faster transit time, which reduces risk for astronauts. Reducing transit time is a key component for human space missions, as longer trips require more supplies and more robust systems.